t1302: don't create unused file

t1302: don't create unused file

Test 'gitdir selection on unsupported repo' in t1302-repo-version.sh
writes output of a "git config" invocation to file "actual".  However,
the test doesn't have any assertions for the file.  The file was used by
this test until commit b9605bc4f2 (config: only read .git/config from
configured repos, 2016-09-12), before which "git config" was expected to
print the bogus value of "core.repositoryformatversion" to standard
output.

Don't redirect output of "git config" to file "actual" in test 'gitdir
selection on unsupported repo'.

Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>